Phase Separation Made Visible

This glaze separates into two phases with different viscosities.
With fortuitous luck, the glaze has .2% Crome Oxide, which colored one of the phases a deap mustard, the other not at all.

The low viscosity phase, described as llw (liquid like water) flows down vertical walls and pools in the bottom of the bowl.
The stiffness of the high viscosity phase is seen in the unhealed bubbles left behind as the llw phase burbbled
out in its 'spring thaw', and slid down the pot leaving it, the stiffer phase, behind.

The radically difference in the viscosities is revealed by the difference in color of the two phases.
Possibly this is the result of the difference in solubility of chrome in the two phases which left most of the chrome
in the low viscosity phase. Alternatively chrome produces more intense color in the low viscosity phase.
It doesn't matter, we have differentially dyed the two phases.

The result as seen below - the upper wall of the pot, both inside and outside is white.
The lower part of the wall, and the inside bottom of the pot is yellowish tan.
Between the upper white, and lower tan, is a region of intermixed streaks of the two colors, i.e. of the two phases.

firing to cone 10 in oxidation

Firing Profile

Up Fire profile

150 deg F an hour to 250 deg F

400 deg F an hour to 2050 deg F

120 deg F an hour to 2240 deg F

60 deg F an hour to 2290 deg F with a hold of 15 minutes at 2290 deg F

60 deg F an hour to 2310 deg F with a hold of 20 minutes at 2310 deg F

Down Fire Profile

A half hour hold at 1750 deg F

A three hour hold at 1700 deg F

slow downfire at 25 deg F an hour in the interval 1700 deg F to 1650 deg F

A one hour hold at 1650 deg F

Clay body is a grolleg porcelain from Tacoma Clay Art Center.